Re-take - Useful Information for 2394 :

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Q/As 2394 .

Which of the following is the minimum short circuit test current for a low résistance ohmmeter .

50mA
100mA
200mA
300mA

This is the requirements for the test instrument , as identified in BS-7671 Regulation 612.2.1. & GN-3 .

 

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Q/As 2394 .

A continuity test is to be carried out and the instrument has been confirmed as being in calibration and undamaged , which of the following is the remaining check that needs to be carried out to confirm the instrument is suitable to use .

it is set to 230V a.c.
The battery is in a satisfactory condition
The leads comply with GS-38
it is set to read high values of résistance

The condition of the battery is the remaining check to be made on the test instrument to confirm it is suitable for use . Where the test voltage is ≤ 50V a.c. the requirement for GS-38 compliant leads is not necessary , providing the maximum short circuit is unlikely to cause a high energy flashover , The maximum current for this test is ≤ 200mA , therefore GS-38 compliant leads are nut required

 

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Q/As 2394 .

Which of the following factors directly affects the conductor résistance of a cable .

a) Insulation and CSA
b) Length and CSA
c) Length and Insulation
d) Load current and CSA

of the four options given , ( b ) is the only one in which both components will directly affect the conductor résistance , Load current will only have an indirect effect on conductor résistance by raising the conductor temperature .

 

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Q/As 2394 .

Two identical cables are connected in parallel , Which of the following describes the effect on the combined conductor résistance compared to the single cable .

Doubled
Quartered
Halved
No effect

The two cables will have the same résistance , which when connected in parallel will result in their combined résistance being half that of one single cable .

 

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Q/As 2394 .

Which of the following factors affect the insulation résistance of a cable .

Conductor cross-sectional area
(b) Cable length
Installation method
Load current .

of the four options given ( b ) is the only one which will have an effect on the insulation résistance of the cable .

 

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Q/As 2394 .

Four identical circuits are connected to a distribution board , Which of the following describes the effect on the combined insulation résistance at the ( DB ) when compared to that of a single circuit .

Doubled
Quartered
Halved
No effect

When a number of circuits are connected at a distribution board the cables are connected in parallel and so insulation résistance will be lower . in this case there are four identical cable connected in parallel and so the combined insulation résistance will be a quarter of the insulation résistance of a single cable . if the cables' insulation résistances are extremely high then this effect may not be registered by the test instrument , as the overall insulation résistance of the combined circuits may be above the upper limit of the test instrument .

 

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Q/As 2394 .

A test for continuity of circuit protective conductors is carried out at every point on a circuit , Which of the following describes the purpose of this test .

To confirm correct polarity
To confirm the conductors are the correct CSA
To determine the ( R1 + R2 ) value for the circuit
(d) To confirm exposed conductive parts are connected to the MET .

of the four options given , is the only one which identifies the purpose of the test . The other three may be determined as a result of the test ,
depending on the method used , but are not the purpose of carrying out the test .

 

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Q/As 2394 .

Which of the following correctly describes the relationship between prospective fault current and the fault current rating of a BS-EN-60898-1 circuit breaker .

( Ipƒ ) ≥ ( Icn )
( Ipƒ ) ≤ ( Icn )
( Ipƒ ) ≤ ( In )
( Ipƒ ) ≥ ( In )

The ( Icn ) of the circuit breaker is the maximum current the circuit breaker can safely disconnect . although it may then no longer be serviceable . to meet the requirements this value must be equal to or higher than the maximum fault current which may occur .

 

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Question 2394 :

What is faster that Usain Bolt , My fingers typing . Gentlemen please hit the thank you button at your own leisure

 

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Q/As 2394 .

Which of the following is not a method for determining prospective earth fault current at the origin of an installation

Enquiry to the DNO
Direct measurement
Calculation using measured ( Ze ) and the supply voltage .
(d) Calculation using measured ( Zs ) and the supply voltage .

prospective fault current is measured to determine the maximum fault current which may occur , Any impedance measurement taken at the end of a circuit will be higher than that at the origin of the circuit , As a result the value obtained from the calculation in ( d ) is not going to produce the maximum value .

 

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Gentlemen am Not downloading this for fun . Your Arse is on the line here . ( Time & Money ) Forewarned is forearmed

On your own Head 2394 / 5

Take Heed .. from C&Gs .. " Warning "

Answer that describes dangerous techniques and a heavy penalty will be applied to answers that describe invalid procedures

The installations being inspected and tested are generally energised , unless information is given to the contrary . ◄◄◄
As a result the need to isolate in order to carry out certain tests must be included in the test process . The description would generally need to include :

the need to obtain permission , to safety isolate and lock off and to retain the key .
A description of the actual safe isolation process would only need to be provided where expressly asked for in the Question .

This qualification relates to the periodic inspection of electrical installations and so encompasses the preparation , client discussion and the inspection , testing and reporting process , The testing process will include the need to confirm that test results are compliant with the requirements of BS-7671: Candidates will also need to identify non-compliances and award appropriate classification codes , Candidates will also be expected to identify the safety and practical aspects of periodic inspection .

Inspection:
The inspection process is a vital part of the periodic inspection process , many conditions may be identified during the inspection which would not be revealed by testing alone . Candidates are expected to be aware of the areas to be inspected , the actual items to be checked and the human senses to be Used whilst inspecting those items , Recording the outcome for each inspection item is also a requirement of the reporting process .

Candidates should be aware that the Schedule of inspections for the periodic inspection of installations provided in BS-7671: & GN-3 , together with the ( Examples of items requiring inspection given in BS-7671: , Appendix 6 ) provides detailed information on the items of inspection for these installations , Candidates should become familiar with the items they are to consider , inspect and record and this will greatly improve both their understanding of the inspection process and their success in any related questions .

( How to not screw UP ) ... Read the related Questions

Confirmation of compliance ; of the installation with the requirements of BS-7671: forms part of the periodic inspection process , The source document generally identifies that all testing is carried out at an ambient temperature of ( 20ºC ) This means that test values will not be at normal operating temperature and so this must be considered and where necessary compensated for .

 

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Younger viewers . making you Aware , The answers are always in front of you . BS-7671:2011: & GN-3

Question Test Sheet
This paper relates to a " Closed book Exam " & therefore candidates should attempt the exam paper with no study-notes or text books .

Q) Minor Electrical Installation Work Certificate does not require a record of :
recap ; R/P.393. Your Q .

System earthing arrangements ... Part 2 : Installation details .
Departures , if any BS-7671:2008: ... Part 1 : Description of minor works
Method of fault protection ... Part 2 : Installation details .
Prospective fault current .

 

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Younger viewers . Just knocked up this for an Example . Stretching it

A New installation is protected against faults by ( ADS ) When inspecting this method of protection , which of the following is not a essential check .

Your Q . Protective Conductors

a) Earthing conductor .
b) Circuit protective conductor(s)
c) Main protective bonding conductor(s)
d) Fire barriers

R/P.27 . Earthing Conductor is defined as “ A protective conductor connecting the Main Earthing Terminal of an installation to an earth electrode or to other means of earthing”

Protective conductors for Earthing are known as Circuit Protective Conductors (CPCs)
R/P.27 . Earthing : Connection of the exposed-conductive-parts of an installation to the main earthing terminal of that installation .

R/P.27 . Equipotential bonding is defined as: “ Electrical connection maintaining various exposed-conductive-parts and extraneous-conductive-parts at substantially the same potential ”

543.2.1. Types of Protective conductor .
A protective conductor may consist of one or more of the following :
(i) single - core cable
(ii) conductor in a cable .

542.4.1. In every installation a main earthing terminal shall be provided to connect the following to the ( Earthing conductor )
(i) The circuit protective conductor(s)
(ii) The protective bonding conductor(s)

recap ; R/P37 . Fig 2.1.

1 , 2 , 3 , 4 , Protective conductors .
Circuit protective conductor(s)
Main protective bonding conductor(s)
Earthing Conductor
4 .. Where required .

 

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Principles , practices & Legislation for the periodic inspection of electrical installation . 2395-302 .

Written Examination

in this paper you will often be asked to provide longer answers for questions that ask you to " describe " or " explain " These are often related to inspection and / or test procedures and you are required to demonstrate your knowledge of the inspection and / or test process . ( 10 )

example ;
Describe , in detail , the procedure for carrying out a test to confirm , the continuity of the main protective bonding conductor connected to the water installation pipework .

there are a number of pointers in the question , The answer is worth 10 marks and the question asks for " detail " so a full description is required .

As this examination only considers periodic inspection , you can determine that the installation is energised , you would always need to confirm that it is safe to isolate the installation or circuit and state that safe isolation is carried out . On occasions the question may state that the permission to isolate has been given or safe isolation has been carried out

Such questions may also be preceded by a number of auxiliary questions relating to the actions required before or after the test concerned , in such cases these items would not need to be repeated in the procedure .

There is no such indication for this question and so the requirements must be included and so you will need to include obtaining permission and the isolation procedure in your description .

Option 1 ;
The answer could be provided as a description of the process in a " story " format , as in the following .

" " story format "
I would obtain permission from the client to isolate the installation , carry out safe isolation of the whole installation , lock off and retain the ( unique key ) I would then disconnect one end of the main protective bonding conductor . I would select a low-résistance ohmmeter , check condition and function , select a suitable long test lead and ( null the test leads ) , I would connect one test lead to the disconnected main protective bonding conductor and the other lead to the far end of the conductor , Test and record the results , I would then reconnect the main protective bonding conductor before reenergising the supply "

This answer and similar variations are perfectly acceptable and you would obtain the marks for the question , however , it does rely on the procedure being written down correctly the first time without missing any steps , it involves a considerable amount of writing and it is often difficult to spot any errors during the examination when you read back through your answer .

Option 2 ;
The answer can be structured as a set of bullet points .
• Obtain permission to isolate the supply
• Safety isolate , lock off and retain the key . PS unique key
• Disconnect the main protective bonding conductor at one end
• Select a low-résistance ohmmeter , check condition and function
• Select a suitable long test lead
• Null the test leads
• Connect the test leads to the disconnected bonding conductor and the far end .
• Test and record the result
• Reconnect the main protective bonding conductor before reenergising the supply

There is plenty of space to write down your answer . so you can leave a space between each bullet point , giving you the opportunity to add an additional line in later if you have missed a step in the process , you can also read through your answer much quicker and identify any omissions

Additional bullet points may be added at the end if you find you have missed out some information providing they identify when the action is carried out . for example if you find you have omitted to null the test leads the final bullet point could be added as ;

• Before carrying out the test the test leads should be nulled .

The second option , with the use of the bullets points , is generally quicker to complete , less prone to errors or omissions and clearly demonstrates your understanding of the test process , you can try both methods to find out which best suits you , however , Option 2 is strongly recommended .

it is important to recognise the need to carry out testing in a way that does not put yourself or anyone else at risk , also the test must be carried out in such a manner that produces valid results . No marks will be awarded for an answer that describes dangerous techniques and a heavy penalty will be applied to answers that describe invalid procedures .

 

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What will be asked of You . 2394

Be able to test electrical installations prior to them being placed into service

You are required to be able to :
Select the test instrument(s) and their accessories for tests to include :

Continuity .
Insulation résistance .
Polarity .
Earth electrode résistance .
Earth fault loop impedance .
Prospective fault current .
RCD operation .
Phase sequence .
Functional testing .

Carry out tests in accordance with BS-7671: & GN-3 .
to include :
Continuity including
□ main protective bonding conductors'
□ circuit protective conductors'
□ ring final circuits
□ insulation résistance
□ polarity
□ external earth fault loop impedance (Ze)
□ system earth fault loop impedance (Zs) ... ( Z impedance , s system ) Zs
□ prospective fault current
□ RCD operation including additional protection
□ phase sequence
□ functional testing

Confirm compliance by verifying test results

Complete appropriate documentation in accordance with the BS-7671: GN-3 , including :
• Electrical Inspections Certificate
• Schedule of Inspections
• Schedule of Test results

Be able to commission electrotechnical systems and equipment .

You are required to be able to :
□ Clarify the commissioning procedures with relevant persons .
□ Carry out the commissioning of circuits , accessories and equipment to confirm functionality .

 

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2395-01 . Understand what is being asked of You . ( 1 )

Outcome 1 , Understand the requirements for completing the safe isolation of electrical circuits and installation
You are require to be able :
□ State : the requirements of the Electricity at Work Regulations for the safe inspection of electrical systems and equipment
□ State : specify the appropriate procedure for completing safe isolation
□ State : the reasons for carrying out safe isolation
□ State : the implications of not carrying out safe isolation
□ Identify : the Health & Safety requirements which apply when inspecting , testing and commissioning electrical installations and circuits

Outcome 2 , Understand the requirements for inspection , testing and recording the condition of electrical installations
You are require to be able :
□ State : the purpose of periodic inspection of electrical installations
□ State : the requirements of periodic inspection
□ Identify : the relevant documents associated with the inspection & testing and condition reporting of an electrical installation

Outcome 3 , Understand the requirements for completing the periodic inspection of electrical installations
You are require to be able :
□ Select : appropriate items to be checked during the inspection process
□ Identify : the human senses which can be used during the inspection process
□ State : how the senses can be used during the inspection process
□ Specify the requirements for the inspection of electrical installations in service

Outcome 4 , Understand the difference between periodic inspection and initial verification
You are require to be able :
□ State : the reasons for requiring a periodic inspection as identified in GN-3
□ State : the need to determine the Extent & Limitations of a periodic inspection with the client and interested third parties before work begins
□ Explain : the application of sampling when carrying out periodic inspection & testing to include:

• Factors which determine the extent of sampling
• Situations where sampling may not be appropriate
• Identify the need to record agreements with the client and third parties on the condition report
• Explain the reasons why testing may be undertaken in a different order to that identified in BS-7671: for initial verification
• Identify the considerations which need to be made during a periodic inspection to ensure the safety of the persons & livestock on the premises
• State the purpose of the observations and classification codes in regards to :
□ the observations to be recorded
□ appropriate recommendations to be made

• State the action to be taken if a dangerous situation is identified during the periodic inspection as identified in BS-7671: & GN-3
• Explain the action required by the inspector when the Extent & Limitations agreed may not be achieved on site
• Explain the difference between defects and non-compliances
• Explain why fault finding and remedial work does not form part of the periodic inspection process

Outcome 5 , Understand the requirements for safe testing of electrical installations which have been placed in service
You are require to be able :
□ State : the tests to be carried out during the periodic inspection of an electrical installation in accordance with the BS-7671: & GN-3
□ Identify : the appropriate instrument for each test to be carried out in terms of :
• Checks to confirm the instrument is fit for purpose
• Identifying the right scale / settings of the instrument appropriate to the test to be carried out
□ Specify the requirements for the safe use of instruments to be used for testing and commissioning , to include :
• Checks required to prove that test instruments and leads are safe and functioning correctly
• The need for instruments to be regularly checked and calibrated

 

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2395-01 . (2)

Outcome 6 , Understand the requirements for testing before circuits are energised
You are require to be able :
□ State : why it is necessary to verify the continuity , to include :
• protective bonding conductors
• circuit protective conductors
• ring final circuit conductors

□ State : the methods for verifying the continuity , to include :
• protective conductors
• ring final circuit conductors
□ Explain : the factors that affect conductors résistance values
□ Specify : the procedures for completing insulation résistance testing
□ State : the effects on insulation résistance values that the following can have :
• Cables connected in parallel
• Variations in cable length
□ Explain : why it is necessary to verify polarity
□ State : the procedures for verifying polarity

Outcome 7 , Understand the requirements for testing energised installations
You are require to be able :
□ State : the method of measuring earth electrode résistance to include :
• installations forming part of a TT system
• Generators and transformers

□ Describe : common earth fault loop paths
□ State : the methods for verifying protection by automatic disconnection of supply
□ Identify : the requirements for the measurement of prospective fault current
□ Specify : the methods for determining prospective fault current
□ Verify : the suitability of protective devices for prospective fault current
□ Specify : the methods for testing the operation of residual current devices
□ State : the reasons for verifying phase sequence
□ State : the methods used to verify phase sequence
□ Describe : the methods used to verify voltage drop
□ State : the cause of voltage drop in an electrical installation
□ Determine : voltage drop
□ State : the need for functional testing
□ Identify : items which require functional testing
□ State : the appropriate procedures for dealing with clients during the periodic inspection process

Outcome 8 , Understand and Interpret test rests
You are require to be able :
□ Explain : why it is necessary to confirm whether test results comply with standard values
□ Analyse test results to determine action to be taken

Outcome 9 , Understand the requirements for the completion of electrical installation condition reports and associated documentation
You are require to be able :
□ Explain : the purpose of an electrical installation condition report
□ State : the information that must be contained within an electrical installation condition report
□ Explain : the requirements for the recording and retention of completed electrical installation condition reports , in accordance with BS-7671:

Outcome 10 , Be able to confirm safety of system and equipment prior to completion of inspection and testing
You are require to be able :
□ Carry out safe isolation procedures in accordance with regulatory requirements
□ Comply with the hearth and safety requirements of themselves and others within the work location during the periodic process
□ Check the safety of electrical systems prior to the commencement of inspection and testing .

 

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2395-01 . (3)

Outcome 11 , Be able to carry out inspection of electrical installations
You are require to be able :
□ Identify : a safe system of work appropriate to the work activity
□ Carry : out a periodic inspection of an electrical installation in accordance with the requirements of BS-7671: & GN-3
□ Complete a condition Report Inspection Schedule in accordance with the requirements of BS-7671: & GN-3

Outcome 12 , Be able to test electrical installations in service
You are require to be able
□ Select the test instruments and their accessories for tests to include :
• continuity
• insulation résistance
• polarity
• earth electrode résistance
• earth fault loop impedance
• prospective fault current
• RCD operation
• phase sequence
• functional testing

□ Carry : out tests in accordance with BS-7671: & GN-3 to include :
• continuity including
º main protective bonding conductors
º circuit protective conductors
º ring final circuits
• Insulation résistance
• polarity
• earth fault loop impedance ( Ze )
• system earth fault loop impedance ( Zs )
• prospective fault current
• RCD operation including additional protection
• phase sequence
• functional testing
• additional protection
• verification of voltage drop

□ Compare test results with standard requirements and previous test results

Outcome 13 , Produce a condition report with recorded observations and classifications
You are require to be able
□ Use information to determine defects and non-compliances to include :
• dwellings
• other premises
□ Complete Electrical Installation Condition Report and associated documents
□ Handover of the condition report to the client with appropriate information and guidance regarding actions to be taken

 

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Putting your answers on paper

it is important to remember when you are answering the questions that the examiners cannot ;

• ask you further questions to establish your understanding , they can only award marks for the information you provide .
• assume what you mean or know , they can only interpret the information they are given in your answers .


Test instruments should be calibrated in accordance with the manufacturer's instructions to ensure accurate test results , in addition to calibration which of the flowing should be carried out and recorded .

□ Regular confirmation of the instruments compliance with BS-7671:
□ Extension of the instrument warranty period
□ Regular instrument accuracy checks
□ Closed circuit voltage checks .

Regular instruments accuracy checks are required to ensure the instrument continues to provide accuracy results , as identified in GN-3 , 4.2. if regular checks are not carried out it may result in the need to re-inspect and test earlier installations , once an instrument defect is identified

Which of the following is the maximum voltage above which test leads must comply with the requirements of GS-38
□ 25V a.c.
□ 25V d.c.
□ 50V a.c.
□ 50V d.c.

Where the test voltages are ≤ 50V a.c. the requirement for GS-38 compliant leads is not necessary where the short circuit fault current is unliky to cause a high energy flashover , test current for this test is ≥ 200mA

Which of the following requirements form GS-38 applies to test equipment which requires more than one test lead .
□ The leads must be at least 1m in length
□ The leads must have a CSA of at least 1.5mm[SUP]2[/SUP]
□ The leads must be colour coded for identification ... is the only one of the listed items described in GS-38
□ The leads must be permanently attached to the instrument .

 

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Remember , What grades . Pass or Fail .

Which of the following instrument must be used to measure the earth electrode résistance for a standby generator .... ◄►( PS keep this in mind )
□ Earth fault loop impedance
□ Insulation résistance tester
□ Low résistance ohmmeter
□ Earth electrode résistance tester .. PS , I no off two Electricians' that got this on 2394.

There is no return path for the current when testing the earth electrode for a transformer or generator , Therefore the test must be undertaken using an Earth electrode résistance tester and not an earth fault loop impedance tester . The other options are not suitable .

Which of the following is not a method used to determine that automatic disconnection of supply for a final circuit is achieved .
□ Direct measurement of ( Zs ) at the furthest point on the circuit
□ Adding the measured value of ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) the ( Ze ) found by enquiry
□ Adding the measured value ( Ze ) and the measured value of ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) for the circuit
□ Measuring the prospective fault current at the furthest point on the circuit

Prospective fault current is measured to determine the maximum fault current which may occur at the point where protective devices are installed to ensure they are able to safely disconnect the fault current. Any measurement taken at the end of a circuit will be lower than that at the origin of the circuit and so not the maximum value

The purpose of the measurement of prospective fault current at the origin of an electrical installation is to determine whether
□ The required disconnection time is met
□ The earth fault loop path can withstand the fault current
□ The protective device can safely disconnect the maximum fault current
□ Supplementary earth fault path are required

Prospective fault current is measured to determine the maximum fault current which may occur at the point where the protective device is installed to ensure the device is able to safely disconnect the fault current

Which of the following is not a method for determining prospective earth fault current at the origin of an instrument
□ Enquiry to the DNO
□ Direct measurement
□ Calculation using measured ( Ze ) and the supply voltage
□ Calculation using measured ( Zs ) and the supply voltage

Prospective fault current is measured to determine the maximum fault current which may occur , Any impedance measurement taken at the end of a circuit will be higher than that at the origin of the circuit , As a result the value obtained from the calculation in ( d ) is not going to produce the maximum value